1. Field of the Invention
One embodiment of the invention disclosed herein relates to an electric double layer capacitor and a manufacturing method thereof, and a lithium ion capacitor and a manufacturing method thereof.
2. Description of the Related Art
In recent years, technologies of energy storage devices such as secondary batteries and electrochemical capacitors have been developed.
As electrochemical capacitors, hybrid capacitors such as lithium ion capacitors (see Patent Documents 1 and 2), electric double layer capacitors (EDLC) (see Patent Documents 3 and 4), and the like have been developed.
Such an electrochemical capacitor includes a positive electrode having a positive electrode current collector and a positive electrode active material layer, a negative electrode having a negative electrode current collector and a negative electrode active material layer, and an electrolyte between the positive electrode and the negative electrode.
Surfaces of a positive electrode active material and a negative electrode active material of an electric double layer capacitor, and a surface of a positive electrode active material of a lithium ion capacitor are each provided with an electric double layer. The electric capacity is increased as the area of the electric double layer is increased, that is, as the surface area of the positive electrode active material or the negative electrode active material of the electric double layer capacitor, or the surface area of the positive electrode active material of the lithium ion capacitor is increased (see Patent Document 5).